Process of treating tall oil



Patented my 1, 1940 UNITED STATES PATENT OFFICE PROCESS OF TREATING TALL OIL .No Drawing. Application July 7, 1938,

. Serial No. 217,974

14 Claims.

The invention relates in general to the refining-of talloil and in particular to a. process of separating the fatty acids from the resin acids normally present in tall oil.

Tall oil or talloel which literally means pine oil is the resinous and fatty by-product obtained in the production of paper pulp from resin-bearing woods by the so-called sulphate process. In the sulphate process wood is digested lo-with an alkaline liquor containing sodium sulphate during which operation tall oil and soaps thereof accumulate on the surface of the wasteliquors. The main constituentspf this oil after acidification comprise fatty acids and resinic I 15 acids each of which are valuable commodities in substantially pure form. Various processes have been proposed in an attempt to effect a separation of tall oil into its main constituents, i. e. fatty acids and resin acids. One process comprises 10 esterifying the fatty acids in tall oil with a low boiling alcoholand separating the resulting fatty ester from the free rosin acids by alkali extrac-\ so distilled off. While the foregoing and other known processes have been employed with varying degrees of success, the fact remains that only a partial separation is effected thereby. The resulting fatty acids and their esters are invariably contaminated with appreciable quantities of resin acids.

The general object of the invention is'to obviate the foregoing and other disadvantages.

A specific object of theinvention is to provide 40 a process of recovering from tall oil both the fatty acids and the resin acids; each in a substantially pure and uncontaminated state.

A further object of the invention is to provide an improved and more efiicient process of separating the main constituents in tall oil.

Other objects will in part be obvious and will in part appear hereinafter. It has now been found thata more complete separation of tall oil into its fatty and resinous 5o constituents can be efiected according to the invention by first subjecting the fatty acids in tall oil to the esterifying action of an alcohol of the kind that will result in esters of relatively high vapor pressure and esterifying the resin acids with a different alcohol of the type that produces partially or completely refined state.

- like may be .used. Esterification of the resin acids For a fuller understanding of the nature and objects of the invention, reference should be had esters of low vapor pressure. The resulting mixture comprises relatively low boiling fatty'acid esters and higher boiling resin esters. The fatty acid esters may be distilled off under reduced pressure from the resin esters with or without the 5 useof steam distillation. The fatty acid esters thus obtained are practically free from contamination with resin acids or esters thereof which remain in the still.

The invention accordingly comprises rthe sevl0 er-al steps and the relation of one or more of such steps with respect to each of the others thereof, which will be exemplified in the process hereinafter disclosed, and the scope of the invention,

will be indicated in the claims. 16:

In carrying out the process of the invention the tall oil to be treated may be in the crude or Any suitable relatively low boiling alcohol having a low. carbon content preferably not more than 5 car- 20 bon atoms may be used in the esterification of the fatty acids. Examples of. such alcohols include, inter alia monohydric alcohols such as the methyl, ethyl, propyl, isopropyl, butyl, isobutyl,

etc. alcohols. For the esterification of the rosin 25.

acids, it is preferred to employ polyhydric alcohols, such as glycerol, glycol, diethylene glycol,

triethylene glycol,'propylene glycol, sorbitol, mannitol or any other alcohol that will produce resin esters having a boiling point sufliciently high with 30 respect to that of the fatty acid ester formed to. permit a complete separation of the latter by distillation. While any suitable polyhydric alcohol may be used, it is highly preferred to employ glycerol for various reasons including cost and efficiency of operation.

During the step of esterifying the fatty acids,

suitable catalysts, such as sulfuric acid, hydrochloric acid, naphthalene-fl-sulfonic acid or the may be carried out without the use of a catalyst,

but it is preferred to accelerate the reaction by addition of such catalyzing agents as finely divided zinc, tin, zinc oxide, magnesium oxide or the like.

to the following examples which are given merely to furthr illustrate the invention and are not to be construed in a limiting sense, all parts given being by weight:

Example I of methyl alcohol and 3 parts of sulfuric acid. The excess alcohol is then distilled off at reduced pressure and the product of reaction consisting of a mixture of methyl esters of fatty acids and of free resin acids is washed free from sulfuric acid. 3 parts of glycerol of 98% strength are then added and the mixture is heated at 280 C. for 8 hours. At the end of this period the acid value has dropped below 2.0. The methyl esters of the fatty acids are then distilled off at a pressure of 2 mm. mercury between 145 and 165 C.

The methyl esters consist of a straw-colored liquid, are substantially free from rosin and have an acid value of 1.9. They may be used as such in the various industries or they may be split into their fatty acids, or they may be sulfated, phosphated or hydrogenated according to-known procedures. The still residue consisting mainly of glycerides of the resin acids is a viscous browncolored oil having an acid value of 0.45.

Example II Gaseous hydrochloride is passed into 30 parts of ethyl alcohol until a solution of 5% thereof in the alcohol is obtained. 100 parts of crude tall oil having a rosin content of 37.5% are then added and the mixture is refluxed for 5 hoursto effect esterification of the fatty acids. The excess alcohol is then distilled off under reduced pressure.

6.5 parts of glycerol of 90% strength and .3 part of zinc oxide are then added and the mixture is heated under an atmosphere of CO2 at 235 to 240 C. for 6 hours. The ethyl esters of the fatty acids are then distilled off at 15 mm. mercury between 200 and 220? C. 1

Example!!! 100 parts of a distilled tall oil ,having al-rosin content of 23% are refluxed with 60 parts of nbutyl alcohol and 5 parts of naphthalene-p-sulfonic acid for 8 hours. The excess butyl alcohol is then distilled off at reduced pressure and the naphthalene sulfonic acid is washed out of the mixture. 4 parts of glycerol of 90% strength and .3 part of magnesium oxide are then added and the mixture is heated between 260-to 270 C. for 6 hours or until the acid value has dropped below 5.0. The butyl esters of the fatty acids are then distilled off at a pressure of 3 mm. mercury between 200 and 215 C.

While the present invention is particularly adapted for the treatment of tall oil, it is within the purview of the invention to employ the process for separating resin acids and fatty acids present in any mixture.

Since certain changes may be made in carrying out the above process without departing from the scope of the invention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all the generic and specific features of the invention herein described, and all statements of the scope of the invention, which as a matter of language might be said to fall therebetween.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a process of treating tall oil to separate the fattyacid .components from the resin acid componentsthe steps which comprise esterifying the fatty acids with a low boiling alcohol and subsequently esterifying the resin acids with an alcohol having a higher boiling pointthan the first alcohol.

2. In a process of treating tall oil to separate the fatty acid components from t resin acid components, the steps which comprise esterifying the fatty acids with a monohydric alcohol and subsequently esterifying the resin acids with a polyhydric alcohol.

3. A process of treating tall oil to separate the fatty acid components from the resin acid components which comprises esterifying the fatty acids with alow boiling alcohol, esterifying the resin acids with an alcohol having a higher boiling point than the first alcohol and distilling off the fatty acid esters thus formed.

4. A process of treating tall oil to separate the fatty acid components from the resin acid components which comprises esterifying the fatty acids with a monohydric alcohol, esterifying the resinacids with a polyhydric alcohol and distilling off the fatty acid ester thus formed.

5. A process of treating tall oil to separate the fatty acid components from the resin acid components which comprises esterifying the fatty acids with a monohydric alcohol in the presence of an acid catalyst, esterifying the resin acids with a polyhydric alcohol and distilling of! the fatty acid ester thus formed.

' 6. A process of treating tall oil to separate the fatty acid components from the resin acid components which comprises esterifying the fatty acids with methyl alcohol in the presence of an acid catalyst, esterifying the resin acids with a polyhydric, alcohol and distilling off the fatty acid ester thus formed. 1

-'7. A process of treating tall, oil to.separate the fatty acid components from the resin acidcomponents which comprises esterifying the fatty acids with ethyl alcohol in the presence of an acid catalyst, esterifying the resin acids with a polyhydric alcohol and distilling off the fatty acid ester thus formed.

8. A process of treating tall oil to separate the fatty acid components from the resin acid components which comprises esterifying the fattyaci'ds with a butyl alcohol in the presence of an v acid catalyst, esterifying the resin acids with a polyhydric alcohol and distilling off the fatty acid ester thus formed.

9. A process of treating tall oil to separate the fatty acid components from the resin acid components which comprises esterifying the fatty acids with a monohydric alcohol having not more than 5 carbon atoms in the presence of an acid catalyst, esterifying the resin acids with glycerol and distilling off the fatty acid ester thus formed.

10. A process of treating tall oil to separate the fatty acid components from the resin acid components which comprises esterifying the fatty acids with methyl alcohol in the presence of an acid catalyst, esterifying the resin acids with glycerol and distillingoff the fatty acid ester thus formed.

11. A process of treating tall oil to separate the fatty acid components from the resin acid components which comprises esterifying the fatty acids with ethyl alcohol in the presence of an acid catalyst, esterifying the resin acid with glycerol and distilling oil the fatty acid ester thus formed.

12. A process of treating tall oil to separate the fatty acid components from the resin acid components which comprises esterifying the fatty acids with a butyl alcohol in the presence of an acid catalyst, esterifying the resin acids with glycerol and distilling off the fatty acid ester thus formed.

13. The process of separating the fatty constituents from the resinous constituents of tall oil which comprises esterifying the fatty acids with an alcohol 01 the group that produces fatty acid esters of relatively high vapor pressure, esterii'ying the resin acids with an alcohol of the type that produces resin esters of low vapor pressure with respect to that of the fatty acid estersand separating the fatty acid esters by distillation.

14. A process of recovering the fatty components from a mixture containing fatty acids and resin acids which comprises esterifying the fatty acids with a monohydric alcohol having no more than 5 carbon atoms, esteritying the resin acids 5 with a polyhydric alcohol and recovering the fatty acid esters thus produced by distillation.

ERNEST SEGESSEMANN. 

